1. Field of the Invention
The present invention relates to a casing (cabinet) for audiovisual equipment which casing has holes through which sound is transmitted to the exterior of the equipment from a built-in speaker, and also to a method of producing the same.
2. Description of the Related Art
Presently, in television receivers having built-in speakers, many attempts are made to make the area comprising numerous sound transmitting holes (hereinafter simply referred to as "the hole area") less noticeable in order to present an attractive outer appearance which gives the impression of integrating the hole area with the casing. The objects of such attempts are to allow a viewer to easily concentrate on the screen by eliminating anything noticeable from the area surrounding the screen and to give the outside of the casing a luxurious appearance. In addition to these objects, another object of the present invention is to omit a fractionating process for recycling audiovisual equipment.
FIG. 10A-C show one example of conventional hole areas which are constructed as follows. A speaker net 40 having good air permeability adheres to a punching sheet 41 having numerous holes 42 with a diameter of greater than 0.5 mm. The resultant member is attached onto a plurality of sound transmitting holes 43 having a diameter of approximately 3 mm, which holes are arranged on the front or side surface of a casing (cabinet) 50 of the television receiver.
However, the above construction presents the following problems. Since the speaker net 40 cannot be formed of the same resin material as the casing, but must be formed of a fiber material or a metal gauze, it must be separated and fractionated when the audiovisual equipment is recycled. Moreover, the fibrous speaker net is expensive, and also, a considerable amount of time is required for attaching the speaker net to the punching sheet and the casing.
In small audiovisual equipment which is directly provided with numerous sound transmitting holes for a cabinet, the diameter of the holes is large relative to the thickness of the casing. For example, the holes have a diameter of approximately from 1 mm to 2 mm relative to the casing having a thickness from 0.5 mm to 1.6 mm. Thus, the sound transmitting holes forming the hole area are obviously noticeable and conspicuous in terms of the outer appearance.
Even in a large casing, such as a television receiver, no attempts have been made to decrease the diameter of the holes until they become substantially unnoticeable.
One of the reasons for this is described as follows. According to the conventional technique, it is believed that the diameter .o slashed.D mm of the mass-producible holes must be the same or larger than the thickness T mm of the casing. Consequently, if it is desired that the diameter of a plurality of holes forming the hole area be decreased until they become unnoticeable in terms of the outer appearance, the thickness of the casing must be decreased in accordance with the diameter of the holes, thus failing to ensure the physical strength of the casing.
Another reason is described as follows. It is easily inferred that it will be difficult to technically arrange such numerous unnoticeable fine holes so as to form a hole area, and thus only very low productivity can be achieved.